Pine Wood Derby

[stomachmonkey]

I'd say the only involvement 90% of these kids had in their cars is they may have been in the house somewhere while their dads built them.

Hopefully my boy kicks ass.

[jford]

It's worse than Club Racing.

[stomachmonkey]

Not looking good here.

Was told polishing axles was a no no.

Have heard several dads discuss how many hours they put into it.

[herr_oberst]

How about an adult pinewood derby league.

[widgeon13]

That is most unfortunate, once again another bad lesson taught by some parents during childhood, win at any cost.

I think I should have been born 200 years ago.

[regency]

Funny memory, when I was a kid and in the Cub Scouts.......say about 1967-68, we all got the PWD kit in a milk carton. I think the only rule was that they could not weight over a posted weight.
Anyway, I sanded off the corners, painted it and installed the wheels. I remember my dad helping me add weight ( lead from the top of wine bottles ). Then, when we were about to go to the big race, my dad's carpenter friend suggested we put some graphite on the wheel hubs. We did.

At the race, most of the cars were a work of art and looked super fast. My car looked like a painted block of wood with wheels. Nobody could touch my car, it never got beat all day. I came home with the trophy.

Steve

73 911T MFI Coupe, Aubergine

[widgeon13]

Did it have a duck tail?? or turbo??

[Scott R]

I was on Ebay last night looking for a mirror for a Honda and the third "top category" for the week was "pinewood derby." I had to check it out... People are selling cars on Ebay with photos of their winning times attached.

Also a myriad of other things like dial indicators for wheel alignment. Jigs for wheel alignments, some highly technical stuff.

pinewood derby cars items - Get great deals on Toys Hobbies, Collectibles items on eBay.com!

[nynor]

Originally Posted by herr_oberst

How about an adult pinewood derby league.

they have one. with all kinds of classes. everything from bone stock official boy scout rules, to sky is the limit. you can ship your car for it to be raced, if you cannot make the trip yourself.

[masraum]

I made mine myself with the exception of using the bandsaw to cut out the shape that I'd drawn on the block. We were on a military base and there was a rule about kids in the wood shop. Other than that, I sanded, painted. My dad told me to take some fine grit sandpaper to the axles, and we put a little dry graphite lube on the axles. That was about 1978.

Me 1979

I think this top photo shows 2 years of cars, 1978 and 1979.

[Hugh R]

Dry graphite is sooo last century. That teflon lube is the way to go. My brother ran my son's through a Jet Propulsion Lab mini wind tunnel one year.

[M.D. Holloway]

Can't polish the axles? The only restriction I was awear of was no liquid lubricant is allowed. Its a crap shoot. We looked at it a few different ways every year. I have seem cars win that according to everything we all think we know about physics has no chance but ends up everything! Go figuer.

[porsche4life]

Originally Posted by stomachmonkey

I'd say the only involvement 90% of these kids had in their cars is they may have been in the house somewhere while their dads built them.

Hopefully my boy kicks ass.

Its all in a wedge shape, that weighs EXACTLY the set weight. Get it as thin as you can and not much thicker in the rear... Drilled with lead shot and a plug, make sure the lead has some room to move, gives it a nice SLAM midtrack....

[stomachmonkey]

Here's one of the cars.

It's an aquarium.

That's one talented 8 year old.

[notmytarga]

Last year the Derby Day caught us by surprise. We saw that Scouts were heading into the cafeteria when we went to church. I dropped the family, ran over to check on the rules, pulled my 6 year old son from church and headed home. On the way I gave him the action list. In 45 min we were back. In that time we had silver sprayed the part of the block we had left over from the wedge we planned, hot glued the prepped axles and wheels, added weight (nuts, bolt and a beer faucet ring!), got him into his uniform and zoomed back. He won a few races, but the alignment was curving to the right - a bad handicap.

Last years lineup: Our car was the rough silver one with the hot glued hardware on top.


Last Sunday was our Pack's Derby Day 2011 and our car took 2nd. The hardest part of building the car was keeping my son as interested as I was.

We read through the book that we got last year as a bedtime prep for the next sessions work: Speed Secrets Book

Great book. It details the tips to make three different levels of cars. Winner, Champion and Ultimate. A good idea is to build two cars so that the scout follows the lead and does all the steps on his car. We may try that next year.

We found out about the rules specific to our Pack. We were limited to a 4 1/2 inch wheelbase. I ordered a set of Derby-Worx tools to square the axle holes, prep the wheels etc. I figured that the tools would pay off over the next four years.

Here is my list of important design and prep issues.

1. Weight - shoot for 5.00000 oz. The scale last year weighed lighter than my own (4.9 oz) We ended up drilling wood out of the front. The judges had a weight standard that they set their triple beam balance to. We adjusted the weight on this years car to be 3 grams lighter than last years and then used tungsten putty into a hole under the center of gravity to bring it up to the max allowed. The putty used was about the size of a pea - dense stuff.

2. Center of gravity - 1 to 3/4 inch in front of rear wheels. This requires a light front end and dense weight in the back. The cars start on an incline and then carry their momentum onto a long flat section of track. Having the weight in the back puts more potential energy to work. The book gives templates for drilling out the tail and placing tungsten cylinders in the holes. We added the gun turret as my son's design choice and he was consistent in explaining to everyone that that is where the weight was. The turret is actually a light 1/2" PVC cap and stem which we sawed to shorten. Wood is so light that the holes up front are more design than function. Although they did prove helpful for carrying the car dangling from a finger. We used body filler to seal the weight holes and it is visually inperceptable - stealth.

Aerodynamics - not really a factor at this scale.

3. Axle prep - you have to remove the crimp burrs from beneath the head with a file. Then we straightened the nails with the Derby Worx press and then wet sanded using a drill clamped to the workbench with 600, 1000, 1500, 2000,2500, 3000 followed by metal polish I used on my Fuchs (tripoli and jewlers rouge).

4. Wheel Prep - The new BSA wheels have a rounded inner hub, no real need to taper it again. Polishing the inner rim and hub with 1000 grit and then graphite is vital. The tread surface can get sanded and graphited too. Using a wheel mandrel and drill is the way to go.

5. Alignment - I avoided the axle slots by using the other surface (top) of the block. Redrilling at the required locations with the "Body tool" which acts as a gig with #45 bit to get a straight hole on either side of the block. The car rolled straight enough after placing the wheels that we didn't want to find the enemy of good. It seemed mostly dependant on what we rolled it on. Our old oak table leaves are all a bit warped it seems.

6. Painting - most important part of getting the scout involved. MASK OFF the hub rub area (3/8 inch circle) so that these remain bare wood. After painting, remove masking, mask off paint and rub graphite here.

7. Lubrication - After attending to the wheel hub/body contact points and the wheel /track contact points it is time to make sure there is adequate graphite in the wheel bore. As the Meade book recommends, a hobby paintbrush works great for getting the slippery stuff in there.

8. Break In - spin those wheels! We used a dremel polishing wheel to keep them moving for 10 min or so. Ideally they should spin for at least 20 sec after a finger spin. That's about all ours did - supposably 35 sec is possible!



Derby day actions - I worked with my son so that he was the one who brought he car to the scale and asked me for weight additions. We had competitors behind us and I didn't want to spook them with tungsten putty and hidden holes. I dug into my pocket and pulled out an assortment of items and a few were added to the scale until it was darn close. We took those items and found a quiet place. I then consulted the copy I made of the random garage items which were weighed on an analytical scale I have that was my wife's grandfather's. (It is maybe 80 years old and uses a weight set for grams, beam weight for tenths and a venier labeled belt with gold chain to add weight.) We added up the weight found for the items and made up 4 1/2 grams of tungsten putty which we had made into ~1 gram pieces. Returning to the scale we found we could add a schrader tire valve stem cap (0.3785 grams) I used a razor blade to make a 1/3 gram piece which my son added to the bottom of the car. The presumption was that we were adding the weight into the turret. It is at the center of gravity, but there is a 4% advantage to adding weight low verses high. I'm confident we were within 1/100 of an ounce (1/3 gram).

So right behind me in line is my son's Den/classmate with his car which is the spitting image of the "Ultimate" car (#2 in the picture below) from the book linked earlier.

It has an extended wheelbase, a notched front, non-kit wheels - all things prohibited in the rules E-mailed to most. I'm still presuming that this dad didn't get the rules because Emails are haphazard, especially to two household families.

Being cars 1 & 2 they raced against each other for the first race and our car lost by a half car length. We won every other race by 1/2 to 5-8 car lengths and thus took second place. I mentioned the wheelbase to a few parents who were then concerned that the winner would be disqualified at the Division Derby on 26 March. We will wait and see. The funny thing is the judges were gaga over this car and gave it the Judges award. It also won the "Sickest Car" voted by the boys and the Peoples choice award! Nice car - but who reads the rules and is it only weight that matters to the judges!?

Now I'm wondering if we should make some modifications within the rules. Ideas are: Raise a front wheel so that it rides on three, matched wheels from the same mold, work on those axles till we get 30 sec spins, notch the underside of the front to get an advantage on the starting pin (I hear a bananna shape helps!). Maybe we will add more graphite and call it good!

[Porsche-O-Phile]

I remember it being all about which track lane you drew (random). The cars were hyper-engineered at home by all the kids' dads, but the track was a POS that was stored up in an attic with uneven lanes, ruts, uneven joints and dust still on it. One lane was clearly faster than the others.

I'd say have ONE track (no side-by-side races) and it all comes down to time - apples to apples.

Oh well... I have to say the cars I built with my dad were among the coolest looking - very european 20s/30s roadster look styling to a couple of them. Way cooler than most. Unfortunately no prizes for style.

[David McLaughlin]

Weight location is very important. It needs to far enough back to allow gravity to do it's job at the lower part of the ramp but forward enough to keep the front wheel on the track. polished axles and wheels are next. If the car is smooth and the weight is in the right spot at the highest possible amount, it doesn't mater what the car looks like.

I try to have my boys do as much as is safely possible. My oldest will use the scroll saw on his own but the youngest will only do the larger cuts to keep his fingers away from the saw. Both will polish the axles and wheels while I keep my finger on the drills trigger. Both paint their cars un assisted though my OCD may make me to a couple small touch ups. I'll usually clear the cars as the fumes are pretty strong with clear coat even with a mask. Basically I try to put my hands in to help build the best they car do with guidance.

[LWJ]

Race day is today!

This year was better in a couple of ways. 1) The boy did a lot more of the work. 2) We didn't totally geek out on the car. 3) The car looks nice. 4) It might just be fast.

The boy's cars have always done well - top 5 in 50 car lineups. I finished first in the adult race last year. Anticipation is growing!

Larry

[LWJ]

Results in.

Out of a field of 44 cars. My boy and I were 1st!

Funny. We posted consistent 3.9 sec times and two cars managed 3.8 sec runs. I didn't think we would even be in the finals. Turns out that we made the cut. All cars run on each four lanes once for the qualifying runs. There are absolutely faster lane than others. On the qualifying, we placed first three times and took a second.

When we made the finals, I knew that we would be lucky to have a third place finish, as these other two cars had some blistering times. We took the first heat on the fastest lane. Then took the second heat on the second fastest lane. Then a second and a third finish.

It seems that consistency over ultimate speed wins the day. This year, my boy did a large amount of the work and we didn't put that much effort in. I think the secret is that we had a stable car and didn't do anything to slow the car down inadvertantly.

Good fun all around. It is nice to have a win for my boy. I think we have paid some dues in prior years with all the effort we have put in. This year, we NEVER thought a win was possible. Just wanted to have a good looking car and finish in the top half.

Makes me smile.

Larry

[Rusty Heap]

Mail to NotMyTarga:

Quote of yours: "Now I'm wondering if we should make some modifications within the rules"???????????


Sounds like you're the kind of anall parent who has a SIX YEAR OLD son, with you as the little league coach or parent that takes over from having the kid do his project, with him making the car, not having him learn anything, with you taking over.............shove him aside and you'll do it for him...........

Your delving into the rules on how to modify or "adapt" them (cheat? gasp) such as only having the car ride on 3 wheels for less drag. (per your own quote)

I feel sorry for your son. What lessons have you taught him about basic competitiveness other than winning is everything. ??????

sometimes losses or being in 2nd or 3rd place teaches you more about "life" in general.

he's 6 years old!


As a Kid, I'd rather lose and learn, then win with a father that gave me that win without earning it.......

Just my 3 cents worth.